This invention relates to a means for the prevention of the accidental discharge of oils and other liquid contaminents into sewage systems, streams and other bodies of water, and, to the control of processes requiring regulation of the flow of liquids with differing specific gravities.
Although this invention has application in the prevention of accidental spills, discharges and accidental mixing of many liquids, for simplicity, its application in the prevention of oil pollution will be described.
As is generally known, most oils are immiscible with water and, due to the lower density of the former, tend to rise to the surface of the water.
It has long been the practice to install grease traps, or oil-water separators, in waste water lines which may be contaminated with oil.
In general these devices provide a containment in which the oil and water mixtures are permitted a period of quiescence during which the lighter density oil rises to the surface of the water where it is contained by baffles or walls. The heavier density water is drained from the lower portion of the containment.
When the grease trap becomes full with oil it must be pumped out or the oil removed by some other means. If the oil is not removed, or, if due to an accident, the containment is flooded with oil, then the oil will start flowing out through the water drain.
To reduce the probability of water pollution due to oil spills and discharges of oil in industrial waste water effluents, grease traps, oil-water separators, dikes, holding ponds and other containment devices are installed in great numbers, frequently at the direction of government agencies concerned with environmental protection. In all of these containments it is necessary to provide for drainage of rain or other waste water. If the containment becomes filled with oil while the water drain valve is open then the oil will be discharged, causing pollution.
This invention provides a means to automatically close water drains in such containments to prevent the accidental discharge of oil or other liquid contaminents by utilizing the lower density of the oil to affect a float which in turn seals off the water drain.